Aminothiophenols and their derivatives have various actual and potential uses in commerce. For example, aminothiophenols such as para-aminothiophenol are important intermediates for the synthesis of pharmaceuticals such as antiarthritics, steroid derivatives, and anti-malarials, and are also used as photograph antifogging agents.
U. S. Pat. No. 4,524,217, issued Jun. 18, 1985 to K. G. Davenport and C. B. Hilton, and assigned to the same assignee as this application, teaches the preparation of N-acyl-hydroxy aromatic amines, e.g., N-acetyl-para-aminophenol (APAP), by reacting a hydroxy aromatic ketone, e.g., 4-hydroxyacetophenone (4-HAP), with hydroxylamine or a hydroxylamine salt, to form the oxime of the ketone, and subjecting the oxime to a Beckmann rearrangement in the presence of a catalyst to form the N-acyl-hydroxy aromatic amine. The patent also discloses the preparation of hydroxy aromatic ketones by the Fries rearrangement of aromatic esters such as phenyl acetate or the Friedel-Crafts acylation of phenols using hydrogen fluoride as catalyst and cites several references disclosing these reactions. The entire disclosure of this patent is incorporated by reference.
Auwers et al, Chemische Berichte 58, 36-51 (1925) show the Beckmann rearrangement of a large number of oximes of aromatic ketones, most of which are substituted acetophenones. However, the only attempted rearrangement of the oxime of a hydroxy aromatic ketone was that of the oxime of o-hydroxyacetophenone, but no amine was formed, i.e., the attempted rearrangement was unsuccessful; see page 41.
Ganboa et al, Synthetic Communications 13, 941-944 (1983) show the production of acetanilide from acetophenone by refluxing in a solution of hydroxylamine hydrochloride. There is, however, no suggestion of the synthesis of N-acyl hydroxy aromatic amines such as N-acetyl-para-aminophenol (APAP).
Pearson et al, Journal of the American Chemical Society 75, 5905-5908 (1953) disclose the formation of hydrazones from ketones by reaction with hydrazine hydrate and the rearrangement of the hydrazone to the amide by reaction with sodium nitrite and concentrated sulfuric acid. Specifically, on page 5907 Pearson et al show the rearrangement of p-hydroxyacetophenone hydrazone to p-hydroxyacetanilide, i.e., APAP.
Newman et al, Journal of Organic Chemistry 31, 3980-3984 (1966), teach the formation of O-aryl dialkylthiocarbamates by reaction of a phenol with a dialkyl thiocarbamoyl chloride, and the pyrolytic rearrangement of O-aryl dialkylthiocarbamates to S-aryl dialkylthiocarbamates. Specifically disclosed in Table I is the pyrolytic rearrangement of O-4-acetamido-to S-4-acetamidodimethylthiocarbamate.
Newman et al, U.S. Pat. No. 3,476,791, disclose a process similar to that disclosed in the article cited in the preceding paragraph and was issued to patentees who are the same as the authors of such article. Example 12 of the patent shows the preparation of p-acetamidophenyl dimethylthiolcarbamate from p-acetamidophenyl dimethylthioncarbamate.
Kwart et al, Journal of Organic Chemistry, 31, 410-413 (1966), show the vapor phase pyrolytic rearrangement of various diaryl thioncarbonates to O,S-diaryl thiolcarbonates and of various O-aryl dialkylthioncarbamates to S-aryl dialkylthiolcarbamates.